Direct acting variable pump



April 13, 1967 D. E. RITCHIE DIRECT ACTING VARIABLE PUMP 5 sheets-Sheet 1 Filed Aug. 24, 1964 DOUGLAS E. RITCHIE INVEIIVTOR.

A ril 18, 1967 D. E. RITCHIE DIRECT ACTING VARIABLE PUMP 3 Sheets-Sheet Filed Aug. 24, 1964 DOUGLAS E. RITCHIE INVENTOR.

DIRECT ACTING VARIABLE PUMP Filed Aug. 24, 1964 DOUGLAS E.RITCHIE INVENTOR.

BY if 3 Sheets-Sheet United States Patent 3,314,365 DIRECT ACTING VARIABLE PUMP Douglas E. Ritchie, 8416 Woodhome Road, Tacoma, Wash. 98499 Filed Aug. 24, 1964, Ser. No. 391,404 8 Claims. (Cl. 10338) This invention relates to a new and novel concept in pumps which deliver material from a discharge source on demand at predetermined pressures. More particularly does this invention relate to a unique pump design and principle which enables the pump to deliver on demand at predetermined high pressures without danger of damage to the driving elements of the pump and in such a manner that auxiliary pressure-producing equipment is eliminated.

Homes and industry have numerous applications for pumps which deliver on demand and at predetermined pressures. Many pumps have been produced which will deliver high pressures and/or volumes at a continuous rate. The task of a fluid pump is to transmit material for a specific result. When that task has been completed, the pump must be shut off instantaneously or it will overpressure or overrun such task. Direct acting pumps are not designed to be stopped by back pressure from the outlet or discharge. If such stoppage or back pressure occurs, there is danger of excessive wear and stress on drive elements such as shafts, and the possible breakdown of the pumping chamber. Fluid pumps that cannot be regulated are virtually useless for intermittent application. Thus, the problem becomes in a large sense one of control. Numerous designs and devices have been investigated to give the operator some measure of control over the pumped material. Since no control variable is available in direct drive, as for instance in gas and electrically driven devices, it has been found necessary to control the drive or power input by employing an auxiliary control variable, the most common being pneumatic. Unfortunately, compressed air necessitates an expensive pressure-generating system consisting, among other items, of pumps, tanks, valves, regulators, and the like. Such auxiliary equipment is needed simply to deliver controllable variable power to a second pumping stage. Hence, heretofore known devices have been unable to deliver intermittently and on demand in a single pumping stage or unit.

Regardless of the nature of the drive, the drive side portion has also never been satisfactorily sealed or isolated from the delivery or material-handling side. Since the pressures necessary for delivering viscous materials such as paints are severe, there is the constant and everrecurring problem of leakage from the pumping or material-handling side. For instance, in high-pressure type pumps, a cylinder or piston is most commonly used to drive the pumped material. Due to natural wear in reciprocating piston pumps, leakage around and along the piston becomes excessive and eventually arrives at the point where its flow is greater than the flow of material being pumped. In such a case, the leaking material in some instances flows into and contaminates the drive unit. Some pumps now on the market, because of uncontrollable leakage of lubricating oil and pumped material, are designeed with a catch cup or reservoir to isolate or drain off contaminated pumped material. If the contaminated material is not drained, it will overflow and thus contaminate the entire supply of material. It does not normally take much wear for pumped material to begin leaking around the drive piston past the seals or packing to the driving elemeents. The result, where hydraulic drive is used, is an inter-mixture of pumped material and hydraulic fluid around the drive elements. When the drive side is air-driven, the problem of course becomes one of gradual infiltration by the pumped fluid into all of the elements of the drive mechanism, thereby 1 cutting down efliciency and creating leaks at numerous locations.

The instant pump is designed specifically to overcome the disadvantages enumerated. The action and demand features of this pump are predicated on the reversal of the usual principles of reciprocal pumping. In short, the piston or follower is positively moved only on the rearward or infeed stroke by application of direct pressure and biased to return on the forward stroke by variable spring pressure applied to the follower. Inasmuch as this device will not pump positively on the forward stroke, and because said forward stroke pressure is adjustable and therefore variable, the forward stroke is accomplished at a predetermined pressure. If forward movement of the follower piston is met and repelled by material pressure balancing the drive spring pressure, forward pumping action will cease. Such balancing pressure of course is the result of closing the outlet or discharge. In this way, the forward or pumping stroke can be arrested at any point over the entire range of follower movement. The follower piston will be urged rearwardly by power but restrained from forward movement by the accumulated balancing material pressure. Eliminating the positive drive pumping stroke protects outlet lines and drive elements from the dangers of overloading. In this way, the operator is able to control delivery simply by opening and closing the discharge outlet or nozzle.

In effect, this pumping mechanism has two sections comprising a pumping side and a driving side. In-feed and discharge are accomplished through check valves on the pumping side while a diaphragm or flexible membrane separates the two sections. The drive side of the pump has a follower element which is connected through the flexible membrane to the other delivery elements. The follower mechanism has behind it a spring having a range of predetermined compressive strength in association with an adjustable element, usually threaded, allowing pressure to be varied by adjusting the spring compressive force. The follower element may be likened to a piston in that it moves reciprocally within the drive housing sec' tion. The compression spring moves the follower in the forward or pumping direction. A shaft-driven cam drives the follower in the rearward or in-feed stroke. Direct pressure from the cam is used only to compress the spring. Between the driving and pumping sections is inserted the flexible membrane or diaphragm which effects a leak-proof and lasting seal. In a low pressure application of this invention, the diaphragm can be a pressurebearing element. In high-pressure variations of this invention, the diaphragm cannot be a pressure-bearing element since maximum stresses resulting from pressure are above the burst pressure of known diaphragm material. The design of the pumping elements in the high pressure applications of this pump eliminate leakage of pumped material beyond or outside the pumping portion. With material inlet and outlet valves so placed in the design, passage of material is confined to inlet and pumping cham bers. All gradual leakage which will eventually occur due to natural wear of packing in the pumping portion will return around the pumping elements and merely reenter the inlet or vacuum chamber to be recycled or re pumped through said pumping elements. It will be appreciated that as packing deteriorates, pressure will begin to drop, reflecting the condition of the packing. More importantly, however, the pumped material will not leak into or infiltrate components and parts on the driving side of the pump, thereby to impair functioning of the pump.

Accordingly, it is a prime feature of this invention to provide a pump which effectively isolates the pumping side of the apparatus from the driving side.

Another feature of this invention is to supply a pump which eliminates auxiliary hydraulic and pneumatic pressure-generating equipment and related regulating systems.

Still another feature of this invention is to furnish a pump which is simple in design, rugged in construction, and economical to produce, as well as being dependable, compact, and readily portable.

Yet another feature of this invention is to provide a pump which can be driven from many types of commonly available power sources, such as motors, both electric and gas-driven, power take-offs, and the like found around homes, shops, and plants.

A further feature of this invention is to provide a pump which eliminates the aggravating problems of leakage and contamination of pumped fluid.

A still further feature of this invention is to supply a self-regulating pump which delivers upon demand by the opening and closing of a discharge or outlet nozzle without danger of damage to the components of the drive side of the pump.

An even further feature of this invention is to provide a pump which allows the pressure to be varied and adjusted according to the desires and needs of the operator.

Other objects, advantages, and features will become subsequently apparent in the details of construction and operation as will be more fully hereinafter described and claimed. Reference will be had to the accompanying drawings, forming a part hereof, wherein like numerals Will refer to like parts throughout, and in which:

FIGURE 1 is a low pressure embodiment of this invention in cross section, showing the diaphragm as a pressure-bearing element;

FIGURE 2 is a partial cross section view in elevation through the midline of the follower element and its camdriving feature shown in FIGURE 1;

FIGURE 3 is an elevational cross section view of another embodiment of this invention which is designed to operate at high pressures, and in which the diaphragm is not a pressure-bearing element; and

FIGURE 4 is an elevational cross section view of another embodiment of this invention in which the pumping side is essentially the same as in FIGURE 3, but in which the drive side of the pump utilizes a spring-loaded ram forwardly driven by the cam.

Referring now to the embodiment of FIGURE 1, it will be seen that the pump is comprised of a two-part housing, The drive or main housing 12 is generally cylindrical and somewhat elongated, having open rear end 14 and inner threaded surface 16. It will be noted that the wall of housing 12 is of substantial thickness to safely enclose the pump-driving elements. The forward end of housing 12 is provided with a belled or flaring annular flange portion 18 which in turn has a peripheral bolt-receiving section 20. A flexible but non-resilient type diaphragm 22 is secured to the peripheral portion 20 of flange 18 by a forward pump section housing generally designated by the number 24. Forward pump section has a frusto-conical portion 26 beginning at about the point of juncture of flange 18 and its peripheral portion on the housing. Said frusto-conical section narrows forwardly and inwardly and has thereon the inside annular flange 28. The outer edge of forward housing 24 also has a peripheral portion 36 which coincides generally in diameter and area with the peripheral portion 20 of the main housing. As can be seen, the forward and rear housing are attached together at their peripheries by bolts or other conventional means 32 in such a way that the diaphragm 22 is secured therebetween to form a fluidtight seal. Diaphragm 22 is preferably made of nonresilient, non-stretchable type plastic or synthetic rubber of relatively heavy thickness. The diaphragm should be so formed that enough slack or flexibility is provided to allow it to flex within the chamber 34 defined between housings 12 and 24.

In FIGURES 1 and 2, the primary drive element is a round, piston-like follower means, generally designated by the number 40. Follower 40 has a diaphragm end surface 42 and rear or spring-engaging surface 44. Follower means 46 is positioned in such a manner that normally diaphragm end 42 extends to some extent into chamber 34 defined between the two housings. As viewed inFIG- URE 2, it will be seen that the interior portion of follower means 40 is hollowed out to form cavity 46. Follower cavity 46 will have a non-contact or generally forward sur= face 48 and a tear or contact surface 51 The cavity is formed with a non-contact forward surface to insure that no positive drive stroke is created. Diaphragm end 42 of follower means 40 is provided with a threaded hole 52 for receiving diaphragm securing bolt 55 which in turn is inserted from the pumping side through the center of the diaphragm to secure diaphragm 22 to su rface 42. Extending across the barrel or interior of main housing 12 on a generally horizontal plane is the drive shaft 54 properly journaled within the housing on each side by virtue of bearing surfaces 56 and 58, It will be noted that an appropriate opening is provided in one side of housing 12 to receive the adapter fitting 62 which is secured to the housing, and in which bearings 58 are mounted so that proper assemblage of the unit can be achieved. Shaft 54 is so located that it passes through cavity 46 of the follower. Within the follower cavity 46 is an eccentric or cam lobe 64 mounted by conventional means, as for instance a lock-screw, on the shaft 54. The periphery of cam 64 may be provided with roller bearing structure 68 so as to minimize wear. Cam 64 is arranged with respect to the follower and shaft so that in its position shown in FIGURES 1 and 2, the diaphragm is forward and the low side of the lobe bears on surface 5%).- As the shaft rotates by appropriate drive by motor means through pulley or sprocket 70, the high side of cam lobe 64 swings around so that follower 40 is retracted a predetermined distance into the barrel of housing 12. Thus, there is provided positive mechanical movement of the follower means in a rear direction. Disposed behind rear surface 44 of follower 41) is the substantial compression spring 72, the precise properties of which are governed by the pressures which the pump as a whole is designed to produce. Spring 72 is confined back of follower 40 and inside the rear end 14 of the housing by an adjusting knob 74. Adjusting knob 74 has cylindrical threaded wall portions 76 to engage the interior threads 16 of the hous ing. Thus, compression and hence delivery force of the spring may be regulated to desired predetermined values. Resilient return is provided for the follower so that in the forward or pumping stroke no positive mechanical drives are involved, such as in the positive rear or in-feed stroke.

Pumping action is provided in this unit by the reciprocal or back-and-f-orth flexing of diaphragm 22. Input is achieved by use of conventional one-way check valve devices as those skilled in the art will clearly recognizer An input connection is provided line or hose 80 which directs material into chamber -34 from a supply source through the check valve assembly generally designated by the number 8 2. The positive rearward infeed stroke of follower 4-0 opens the spring-loaded ball in check valve 82 so that material is brought into chamber 34. As cam 64 rotates another spring 72 forces follower 4t) forwardly, driving the material through discharge connection 84; by way of check valve 86. In this particular embodiment, diaphragm 22 is, as stated above, a pressurebearing element and is responsible for pressure delivered through discharge line 84 and check valve assembly '86. Thus, because the diaphragm does act as a pressure-bearing element as well as a seal, this embodiment would necessarily be confined generally to low pressure pumping. It will be appreciated that due to complete sealing between the material-handling or pumping side and the drive side that no leakage occurs from one side to the other.

The embodiment shown in FIGURE 3 involves the same principles as the embodiment in FIGURES l and 2, except that certain modifications have been made in the pumping portion of the device to handle high pressures. This pump has housing 100 for the drive elements, attachment flange 102, rear end 104, and rear end interior threads 106 for receiving adjusting knob 108. A follower means or piston 110 has diaphragm end 112, rear or spring end 114, and internally thereof in cavity 115 the forward or non-contact surface 116 and the rear or contact surface 118. Shaft 121 is mounted on bearings supported in the walls of housing 100 and extends through cavity 115 generally horizontally. Cam lobe 1-20 is mounted on shaft 121 and has the peripheral bearing element 122. Compression spring 1 24 provides energy for returning follower 110 to its forward position. Since this embodiment is intended to deliver higher pressures than the previous embodiment, it is necessary that the pumping portion of the apparatus also be provided with substantial structure. Accordingly, pump portion or housing 130 is generally of the same diameter and thickness as drive housing 1011. Pump housing 139 is considerably shorter, however, and is provided with flange 132 for attachment to flange 102 to join the two housings by the use of bolts 134. A diaphragm 13 6 is interposed between the pump housing and the drive housing. The relatively short housing 130 defines a vacuum chamber 138 interiorly thereof bounded on the rear by diaphragm seal 136 and at the forward end by a closure member 141). A packing head 142 is bolted to forward housing 130 by virtue of elongated bolts or studs 144. Closure member 140 and sealing or packing heads 142 are formed with openings through the central portions thereof, in order to accommodate a pressure piston element generally designated by the number 150.

A connector and inlet unit 152 forming part of pressure element 150 is attached by threaded stud 154 through diaphragm 136 to end 112 of follower 116. Unit 152 has ports 156 towards the rear end thereof which open into a central cavity 157 inside unit 152. A one-way check valve assembly housing 158 contains a commonly known compression spring 161) and closure ball 162 which communicate with chamber 157. Check valve housing 158 also has inlet opening 164 opened and closed by ball 162. Extending forwardly and centrally, from check valve housing 158, is an elongated tube 166 having central passageway 167. Check valve housing 158 is received in the unit 152 where is is rigidly held or secured as by threads or the like. Check valve tube 166 extends through an opening in the closure member 140 into a cavity 168 in the packing head. The cavity 168 extends generally through the entire length of the packing head, and terminates near the rear end thereof to receive a pressure hose or line fitting 170. Cavity 168 is generally of the same diameter as tube 166. A significant potrion of the packing head around cavity 168 is provided with well-known type chevron packing or other type seals 172 for a purpose which will be explained hereinafter.

An inlet opening check valve 174 is installed in the wall of the forward pump portion 130. An adapter or fitting 176 connects to the check valve and receives line or hose 178 leading from the manifold or source of material to the pump. The nature and design of the check valves are not limited except by their ability to function in this environment. It will be seen that direct mechanical tying of pressure element 150 is made with the follower 110. Connection is made through a hole in the diaphragm seal so that element 150 can be secured to the follower. As follower 110, and the entire assembly of elements 152, 158, and 150 are driven to the rear by earn 120, vacuum is created within chambers 138 and 168 so that material is drawn in through 'infeed line 178,

through the check valve 174, and into chamber 138. At the same time as follower element 110 moves rearwardly, pressure element 150 also moves rearwardly. Material then enters pressure element 150 through input ports 156, cavity 157, and into the check valve, tube 166, and chamber 168. Follower means 110 is urged forward by spring 127, the check valve in housing 158 closes, as does infeed check valve 174, to completely close the pumping side. Follower 110 transfers forward movement to pressure element 150, creating pressure within barrel 167 of tube 166 and within the chamber 168 to deliver material from outlet connection 170. In this way, direct pressure on the diaphragm 136 is avoided.

It will be appreciated that a certain amount of flexing takes place in the diaphragm. Sealing means 172 in the packing head prevents material from feeding back into the main chamber 138 around tube 166. It will be appreciated that pressures in chamber 138 are significantly lower than those within tube barrel 167, check valve 158, and packing head chamber 168. Some pressure will be generated in main chamber 138, but flexibility of the diaphragm restricts the pressure from building beyond a confinable point. Since drive shaft 122 in main housing is rotated at conventional motor speeds, reciprocation of follower with the nozzle open is extremely rapid. Therefore, while the pressure element does not handle large quantities of material in any one stroke, nevertheless it does generate positive pressures in accordance with the demand of the discharge element attached to the outlet connection and in sufficient quantity. Nature of the packing head 142 is such that it can be removed very quickly from the pump and new seals 172 put in as the old seals begin to wear and permit leakage therearound from chamber 168 back into the main chamber 138.

The embodiment of FIGURE 4 illustrates an alternative drive structure. The forward or pumping section is essentially the same, if not identical to forward or pumping portion 130 of the embodiment shown in FIG- URE 3, and hence same numbers designating the elements have been applied. The altered drive structure of the embodiment of FIGURE 4 has a cylindrical rear housing generally designated by the number 180. Housing 180 has attachment flange 182 for securement to forward flange 132 by bolts or studs 134. Diaphragm seal 184 is interposed between forward housing 130 and the drive housing 180. The front end of housing 180 is substantially closed by forward wall 186 which is generally formed radially inwardly at right angles to the main housing. The forward surface 188 angles inwardly and rearwardly. The threaded stud 154 is attached to drive means 190 which is in the form of a T-shaped element, the central or longitudinal portion of which attaches to threaded stud 154. An opening is provided in wall 186 to allow for aligned reciprocal movement of drive means 190. A retaining ring or washer 192 is placed on the threaded stud 154 on the rear side of the diaphragm between element 152 and drive means 190. Retaining ring 192 prevents drive means 190 from slipping free or disengaging from the opening in wall 186. Thus its rearward movement is controlled. A cylindrical spring housing 194 is placed within the confiines of housing 180 and contains the main compression or drive spring 196. The head portion of drive means 190 is inside the spring housing while an opening in the forward wall 195 of said spring housing allows the central portion to extend forwardly to the rear side of member 190. The head of drive means 190 abuts the rear or interior surface of forward wall 195 and as can be seen, the central portion is received for slidable reciprocal movement in the opening. The rear end of spring housing 194 is open and threaded on its inside as at 198 to receive the closure adjustment cap 2011. Cap 200 in this instance serves as the pressure adjustment feature for the main compression spring 1%. Elements 200 and 202 make up a length compensating feature so that as cap 200 is tightened to compress spring 196, the counter-threaded follower member 202 is threaded rearwardly to insure that the same length in the drive parts is maintained. Thus, in contrast to the embodiment of FIGURE 3, spring 196 is not compressed in either direction, either during the pumping stroke or the rearward or infeed stroke. Compression of said spring takes place only when back pressure of pumped material overcomes pressure of spring 196. Then, of course, the driven member 190 is held against forward movement. The cam moves spring housing 194 forwardly compressing spring 196. Follower element 202 is formed with the contact or follower surface 296. Shaft 208 has cam lobe 210 with appropriate lock screw 212, and peripheral bearing structure 214. Thus, positive drive \of the whole assembly is obtained from the rear rather than from its front. The open rear end of main housing 186 is closed with a cover element 216 in conventional manner.

A return spring 220 is disposed between the spring housing 194 and the main housing 180 and provides the force for the rearward or infeed stroke drawing material into pumping chamber 138. The inside wall of main housing 180 is offset outwardly and the rear portion of the spring housing is also offset outwardly to define a spring cavity for auxiliary spring 224). This arrangement results in a spring-loaded rearward or infeed stroke and a posi tive forward stroke buffered by spring 196 and member 190 in case discharge is stopped to create a pressure balance. The shaft and cam 210', together with follower 2G2 compress both springs. In the event that the nozzle or discharge control element attached to the pumping outlet 170 is open, the assembly of elements 190, 195, 2.00, and 232 will move forward with the positive drive stroke of the follower.

It will be appreciated by those skilled in the art that a positive material infeed could be incorporated with the various embodiments, thus eliminating the negative or vacuum type infeed action shown.

The foregoing is considered as illustrative only of the principles of this invention. Numerous modifications will occur to those skilled in the art and hence it is not desired to limit the invention to the exact construction and operation shown and described. Accordingly, all suitable equivalents may be resorted to which fall within the scope of the invention.

What is claimed is:

1. A demand controlled, variable pressure pump, comprising: (a) a tubular drive housing having a front end and a rear end; (1b) a reciprocally movable piston follower means of uniform transverse dimension and slidably engaging the inner surface of said housing and located generally at said front end, said follower means including a cavity opening therethrough having a cam follower surface; (c) a drive shaft means mounted in said housing and extending through said cavity, said shaft having a cam lobe means thereon engaging said cam follower surface for moving said follower means rearwardly as said shaft rotates; (d) a compressible pressure spring located to the rear of and bearing on said follower means to urge said cam follower surface against said cam lobe means, said drive housing having spring pressure adjustment means received on the rear end thereof confining said pressure spring; (e) a material pumping housing detachably received on the front end of said drive housing and including a non-resilient, flexible, non-porous diaphragm received between said housings for sealingly isolating one housing from the other, said diaphragm being attached to the forward end of said follower means for reciprocation therewith, and said pumping housing having check valve operated inlet and outlet means for pumped material.

2. A demand controlled, variable pressure pump, comprising: (a) a tubular drive housing having a front end and a rear end; (b) a reciprocally movable piston follower means of uniform transverse dimension and slidably engaging the inner surface of said housing and located generally at said front end, said follower means including a cavity opening extending therethrough, said cavity having a cam follower surface; (c) a drive shaft means mounted in said housing and extending through said cavity, said shaft having a cam lobe means thereon engaging said cam follower surface for moving said follower means rearwardly as said shaft rotates; (d) a compressible pressure spring located so as to bear on said follower means to urge said cam follower surface against said cam lobe means, said drive housing having spring pressure adjustment means received thereon confining said pressure spring between said piston follower and said adjustment means; (e) a material pumping housing detachably received on the front end of said drive housing and including a non-resilient, flexible, non-porous diaphragm received between said housing for sealingly isolating one housing from the other, said diaphragm being attached to the forward end of said follower means for reciprocation therewith, and said pumping housing having one-way check valve operated inlet and outlet means for pumped material.

3. A demand controlled, variable pressure pump, comprising: (a) a tubular drive housing having a front end and a rear end; (b) a reciprocally movable piston follower means within said housing and located generally at said front end, said follower means having a cam follower surface; (0) a drive shaft means rotatably received and mounted in said housing, said shaft having a cam lobe means thereon engaging said cam follower surface for positively moving said follower means rearwardly as said shaft rotates; (d) a compressible pressure spring located to the rear of and bearing on said follower means to urge said cam follower surface against said cam lobe means, said drive housing having spring pres-sure adjustment means received on the rear end thereof confining said pressure spring; (e) a pump housing having front and rear ends and being detachably received on the front end of said drive housing and including an inlet valve and a flexible, non-porous diaphragm: seal received between said housings for sealingly isolating one housing from the other, the inside of said pump housing defining a vacuum chamber enclosed at its rear end by said seal and on its front end by closure head means; and (f) a discharge pressure element within said pump housing connected for reciprocal movement through said seal to said follower means and including inlet ports and an elongated outlet valve housing extending into a pressure outlet cavity in said closure head for generating pressure on pumped material as said follower and pressure element move.

4. A demand controlled, variable pressure pump, comprising: (a) a tubular drive housing having a front end and a rear end; (b) a reciprocally movable piston follower means within said housing and located generally at said front end, said follower means including a cavity opening therethrough having a cam follower surface; (0) a drive shaft means mounted in said housing and extending through said cavity, said shaft having a cam lobe means thereon engaging said cam follower surface for positively moving said follower means rearwardly as said shaft rotates; (d) a compressible pressure spring located to the rear of and bearing on said follower means to urge said cam follower surface against said cam lobe means, said drive housing having spring pressure adjustment means received on the rear end thereof confining said pressure spring; (e) a pump housing having front and rear ends and being detachably received on the front end of said drive housing and including an inlet valve and a flexible, non-porous diaphragm seal received between said housings for sealingly isolating one housing from the other, the inside of said pump housing defining a vacuum cham ber enclosed at its rear end by said seal and on its front end by closure head means; (f) a discharge pressure element within said pump housing connected for reciprocal movement through said seal to said follower means and including inlet ports and an elongated outlet valve housing extending into a pressure outlet cavity in said closure head for generating pressure on pumped material as said follower and pressure element move.

5. A demand controlled, variable pressure pump, comprising: (a) a tubular drive housing having a front end and a rear end; (b) a reciprocally movable piston follower means within said housing and located generally at said front end, said follower means including a cavity opening extending therethrough, said cavity having a cam follower surface; (c) a drive shaft means mounted in said housing and extending through said cavity, said shaft having a cam lobe means thereon engaging said cam follower surface for positively moving said follower means rearwardly as said shaft rotates; (d) a compressible pressure spring located so as to bear on said follower means to urge said cam follower surface against said cam lobe means, said drive housing having spring pressure adjustment means received thereon confining said pressure spring between said piston follower and said adjustment means; (e) a pump housing having front and rear ends and being detachably received on the front end of said drive housing and including an inlet valve and a flexible, non-porous diaphragm seal received between said housings for sealingly isolating one housing from the other, the inside of said pump housing defining a vacuum chamber enclosed at its rear end by said seal and on its front end by closure head means; and (f) a discharge pressure element within said pump housing connected for reciprocal movement through said seal to said follower means and including inlet ports and an elongated outlet valve housing extending into a pressure outlet cavity in said closure head for generating pressure on pumped material as said follower and pressure element move.

6. A demand cont-rolled, variable pressure pump, comprising: (a) a generally tubular drive housing having front and rear ends; (b) reciprocally movable follower means within said housing and located generally toward said front end, said follower means having a drive engaging means thereon; (c) a drive means extending through and received in said housing, said drive means having a follower engaging means thereon engaging said drive engaging means for moving said follower means; (d) a compressible pressure spring means located within said housing and bearing on said follower means to urge said drive engaging means against said follower engaging means, said drive housing having spring pressure adjustment means thereon; (e) a pump housing having front and rear ends and being detachably received on the front end of said drive housing and including an inlet valve and a flexible, non-porous diaphragm seal received between said housings for sealingly isolating one housing from the other, the inside of said pump housing defining a vacuum chamber enclosed at its rear end by said seal and on its front end by closure head means; and (f) a discharge pressure element within said pump housing connected for reciprocable movement through said seal to said follower means and including inlet ports and an elongated outlet valve housing extending into a pressure outlet cavity in said closure head for generating pressure on pumped material as said follower and pressure element move.

7. A demand controlled, variable pressure pump, comprising: (a) a generally tubular drive housing having front and rear ends; (b) a reciprocally movable, generally tubular piston follower means within said housing and located generally toward said front end, said follower means having a drive engaging means thereon; (c) a drive means extending through and received in said housing, said drive means having a follower engaging means thereon engaging said drive engaging means for moving said follower means; ((1) a first compressible pressure spring means located within said drive housing outside said follower means and bearing on said follower means to urge said drive engaging means against said follower engaging means, said follower means having spring pressure adjustment means thereon, a second compressible pressure spring therein and a connector drive means on the front end thereof for relative movement with said follower means; (e) a pump housing having front and rear ends and being detachably received on the front end of said drive housing and including an inlet valve and a flexible, non-porous diaphragm seal received between said housings for sealingly isolating one housing from the other, the inside of said pump housing defining a vacuum chamber enclosed at its rear end by said seal and on its front end by closure head means; and (f) a discharge pressure element Within said pump housing connected for reciprocal movement through said seal to said connector drive means in said follower means and including inlet ports and an elongated outlet valve housing extending into a pressure outlet cavity in said closure head for generating pressure on pumped material as said follower and pressure element move, said outlet valve housing being sealed by said closure head.

8. A demand controlled, variable pressure pump, comprising: (a) a generally tubular drive housing having front and rear ends; (b) a reciprocally movable generally tubular follower means within said housing and located generally toward said front end of said drive housing, said follower means having a drive engaging means on the rear portion thereof; (c) a drive means extending through and received in said housing, said drive means having a follower engaging means thereon engaging said drive engaging means for moving said follower means; (d) a first compressible pressure spring means located within said housing outside said follower means and hearing on said follower means to urge said drive engaging means rearwardly against said follower engaging means, said follower means having spring pressure adjustment means thereon, a second compressible pressure spring therein and a piston connector drive means slidably re ceived within said follower means and extending out of the forward end of said follower means; (e) a pump housing having front and rear ends detachably received on the front end of said drive housing and including an inlet valve and a flexible, non-porous diaphragm seal received between said housings for sealingly isolating one housing from the other, the inside of said pump housing defining a vacuum chamber enclosed at its rear end by said seal and on its front end by closure head means; and (f) a discharge pressure element within said pump housing connected for reciprocal movement through said seal to said piston connector drive means in said follower means and including for movement therewith inlet ports and a generally tubular elongated outlet valve housing extending into a pressure outlet cavity in said closure head for generating pressure on pumped material as said follower and pressure element move.

References Cited by the Examiner UNITED STATES PATENTS 1,597,689 8/1926 Moulet 10337 2,040,667 5/1936 Moulet 103-48 3,120,817 2/1964 Price 103150 FOREIGN PATENTS 587,838 1/1925 France. 1,005,688 12/1951 France.

LAURENCE V. EFNER, Primary Examiner. 

1. A DEMAND CONTROLLED, VARIABLE PRESSURE PUMP, COMPRISING: (A) A TUBULAR DRIVE HOUSING HAVING A FRONT END AND A REAR END; (B) A RECIPROCALLY MOVABLE PISTON FOLLOWER MEANS OF UNIFORM TRANSVERSE DIMENSION AND SLIDABLY ENGAGING THE INNER SURFACE OF SAID HOUSING AND LOCATED GENERALLY AT SAID FRONT END, SAID FOLLOWER MEANS INCLUDING A CAVITY OPENING THERETHROUGH HAVING A CAM FOLLOWER SURFACE; (C) A DRIVE SHAFT MEANS MOUNTED IN SAID HOUSING AND EXTENDING THROUGH SAID CAVITY, SAID SHAFT HAVING A CAM LOBE MEANS THEREON ENGAGING SAID CAM FOLLOWER SURFACE FOR MOVING SAID FOLLOWER MEANS REARWARDLY AS SAID SHAFT ROTATES; (D) A COMPRESSIBLE PRESSURE SPRING LOCATED TO THE REAR OF AND BEARING ON SAID FOLLOWER MEANS TO URGE SAID CAM FOLLOWER SURFACE AGAINST SAID CAM LOBE MEANS, SAID DRIVE HOUSING HAVING SPRING PRESSURE ADJUSTMENT MEANS RECEIVED ON THE REAR END THEREOF CONFINING SAID PRESSURE SPRING; (E) A MATERIAL PUMPING HOUSING DETACHABLY RECEIVED ON THE FRONT END OF SAID DRIVE HOUSING AND INCLUDING A NON-RESILIENT, FLEXIBLE, NON-POROUS DIAPHRAGM RECEIVED BETWEEN SAID HOUSINGS FOR SEALINGLY ISOLATING ONE HOUSING FROM THE OTHER, SAID DIAPHRAGM BEING ATTACHED TO THE FORWARD END OF SAID FOLLOWER MEANS FOR RECIPROCATION THEREWITH, AND SAID PUMPING HOUSING HAVING CHECK VALVE OPERATED INLET AND OUTLET MEANS FOR PUMPED MATERIAL. 